Layered double hydroxides magnesium-aluminum

The selective intercalation of guests into solid hosts offers the potential for application in catalysis and separation science. An excellent case in point is zeolites, which exhibit shape and size selective inclusion properties and are used for an enormous variety of processes [44,45]. Additionally, a munber of layered materials have been reported to possess selective intercalation properties, including layered metal phosphonates [46,47], montmorUlonite [48], magnesium aluminum oxide [49], and layered double hydroxides [50-59]. 

Boclair, J. W., Braterman, R S., Brister, B. D. and Yarberry, F. (1999). Layer-anion interactions in magnesium aluminum layered double hydroxides intercalated with cobalticyanide and nitroprusside. Chem. Mater. 11, 2199. 

The replacement of conventional bases, such as NaOH, KOH and NaOMe, by recyclable solid bases, in a variety of organic reactions, is also a focus of recent attention [27, 40]. For example, synthetic hydrotalcite clays, otherwise known as layered double hydroxides (LDHs) and having the general formula Mg8 xAlx (0H)16(C03)x/2 nH20, are hydrated aluminum-magnesium hydroxides possess-... 

Layered double hydroxide carbonates of magnesium and aluminum are called hydrotalcites (e.g., Mg6Al2(OH)i6 CO3-H2O). They can be used as solid bases before or after calcination to produce mixed magnesium-aluminum oxides.74 They have been used to catalyze the addition of alcohols to acrylonitrile 75 the reduction of ketones with iso-... 

Hydrotalcites are synthetic basic clays, so-called layered double hydroxides (LDHs) of magnesium and aluminum consisting of Brucite-like layers with an overall positive charge with anions (usually OH or in the interlamellar... 

For PNCs, the layered double hydroxides (LDHs) constitute a new class of mainly synthetic, reinforcing nanoparticles. During synthesis, LDHs may be preintercalated with organic anions. Unfortunately, most LDH platelets are thin, f=0.6 0.1nm, small in diameter, d=30 to 40 nm [Wu et al., 2007]), and decompose thermally at T IOTC [Camino et al., 2001]) consequently, their main application has been for absorption of HCl during dehydrochlorination of poly(vinyl chloride) (PVC) and halogenated polymers, or as flame retardants. The flow behavior of polyethylene (PE) with LDHs was reported to be similar to that of CPNCs [Costa et al., 2006]. There are no commercial PNCs with LDHs on the market, but experimental products such as Perkalite, a preintercalated aluminum-magnesium (Al-Mg) LDH, have been... 

Moisture content, % 3-4 Product content aluminum magnesium layered double hydroxide (LDH) modified with rosin (or mixture of rosin and saturated fatty acid) 50-55% LDH ... 

Ethylene-vinyl acetate Magnesium hydroxide aluminum-layered double hydroxide nanocomposites are thermally unstable [94]. 

Nanoclays can be categorized into cationic and anionic types. Cationic nanoclays are based on smectite clays. An example is montmorillonite (MMT), a hydrated Al, Mg silicate that may contain cations such as Na+ and Ca++ between the anionic layers. In contrast, anionic clays contain cationic layers and anions such as Cr and in the interlayer space. Typical examples include layered double hydroxides (LDH) and hydrotalcite (HT), a mostly synthetic hydrated magnesium and aluminum carbonate salt. Whereas MMT is commonly used as a nanofiller to improve thermal, mechanical, and barrier properties, LDHs have many attractive properties that lead to application as surfactant adsorbents, biohybrid materials, antacid food formulations, acid neutralizers, and active pharmaceutical ingredients excipients [37, 13, 28, 14, 35]. 

C. M. Jiao, Z. Z. Wang, X. L. Chen, and Y. Hu, Synthesis of a magnesium/ aluminum/iron layered double hydroxide and its flammability characteristics in halogen-free, flame-retardant ethylene/vinyl acetate copolymer composites. Journal of Applied Polymer Science, 107 (2007), 2626-31. 

Layered double hydroxides (LDHs) are a different kind of layered crystalline filler for nanocomposite formation. Because they combine the flame retardant features of conventional metal hydroxide fillers (magnesium hydroxide and aluminum hydroxide) with those of layered silicate nanofillers (montmorillonite), LDHs are considered to be a new emerging class of nanofillers favorable for the preparation of flame retardant nanocomposites. In the present chapter, recent progress in the study of polymer/LDH flame retardant nanocomposites is reviewed. 

C. Manzi-Nshuti, P. Songtipya, E. Manias, M. M. Jimenez-Gasco, J. M. Hossenlopp, and C. A. Wilkie, Polymer nanocomposites using zinc aluminum and magnesium aluminum oleate layered double hydroxides Effects of LDH divalent metals on dispersion, thermal, mechanical and fire performance in various polymers. Polymer, 50 (2009), 3564-74. 

C. Manzi-Nshuti, D. Chen, S. P. Su, and C. A. Wilkie, Structure-property relationships of new polystyrene nanocomposites prepared from initiator-containing layered double hydroxides of zinc aluminum and magnesium aluminum. Polymer Degradation and Stability, 94 (2009), 1290-97. 

It should be noted that magnesium aluminum layered double hydroxides (MgAl-LDHs) have also been widely used as flame retardants for polymer materials. Similarly, MgAl-LDHs can be synthesized by reaction of aluminum and magnesium salts as precursor and sodium hydroxide as precipitator via the coprecipitation method and other preparation routes. ... 

Group (IV) metal phosphates and phosphonates, transition metal oxides (titanates, silicates, niobates, etc.), layered oxides, and double hydroxides (aluminum, magnesium, iron, etc.) are some of the inorganic compounds used as layered host ma-... 

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